The Walking Brain: Mapping feature-specific cortical responses to naturally unfolding sensory experience in the real world

Understanding how the brain processes the everyday world is fundamental, yet laboratory paradigms exclude self-generated movement, unscripted events, and a continuously evolving multisensory environment. Wearable neuroimaging enables real-world measurement, but linking neural activity to uncontrolled sensory information remains challenging. Here, we extend a feature-based framework from naturalistic movie viewing to everyday behavior using wearable whole-head high-density fNIRS and participant-specific audiovisual recordings during movies and outdoor walking with no explicit task or scripted audiovisual sequence. Luminance- and sound-related cortical maps showed significant spatial correspondence, particularly in visual and auditory regions, whereas face-related correspondence was weaker. Luminance- and face-related maps were reproducible within individuals across repeated walks. Additional exploratory analysis demonstrated, to our knowledge, the first out-of-sample encoding of continuous environmental features during unconstrained real-world fNIRS, predicting cortical activity during held-out walking periods. Together, these findings establish a feature-based framework for linking cortical activity to naturally unfolding sensory experience in everyday behavior.